Gladwell opens his book with a dictionary definition of the word "outlier." It is "something that is situated away from or classed differently from a main or related body," and also "a statistical observation that is markedly different in value from others of the sample."

2. Where is Roseto and who founded it?

Roseto is founded by Italian immigrants in the late 19th century. Most of the early residents are from a town in Naples, also called Roseto, after which the Pennsylvania town is named.

3. What makes Roseto an "outlier" town and how does this fact come to light?

What makes Roseto, Pennsylvania an "outlier" is that the residents are remarkably healthy when compared to other Americans. This fact comes to light almost by accident when a physician and professor named Stewart Wolf visits the town to give a talk in the 1950s and afterward has a discussion with a local physician. This doctor tells Wolf that he has been treating people in the area for many years and that he rarely sees anyone from Roseto die from heart disease.